Asbestos is the generic name given to a specific group of six naturally occurring fibrous silicate minerals which are part of two sub-groups: the serpentine sub-group comprises a single type of asbestos called the chrysotile; and the amphibole sub-group comprises the following types of asbestos: crocidilite, amosite, anthophyllite, tremolite and actinolite. The two sub-groups of asbestos differ in their crystalline structure: the serpentines have a sheet or layered structure, while the amphiboles have a chain-like structure. The chrysotile is the asbestos which is by far the most commonly extracted asbestos type world-wide.
Asbestos can be used advantageously in an important number of industrial applications, such as roofing, thermal and electrical insulation, in cement pipes and sheets, in flooring, gaskets, friction materials, coatings, plastics, textiles, paper, and a number of other products. Its particular composition, coupled with the fact that it is the only naturally occurring fibrous mineral, make it an extremely useful and versatile component.
However, asbestos suffers an important drawback: it can cause diseases if asbestos particles are inhaled in minimum threshold quantities. Since asbestos is a frangible material that frees airborne particles, asbestos particles may be inhaled in significant quantities under specific circumstances.
Some diseases imputed to inhaled asbestos include the following: asbestosis, which is a scarring of the lung tissue which leads to breathing difficulties; lung carcinomas, which are malignant lung tumors of the bronchi covering; and mesotheliomas, which is a cancer of the pleural lining. It is noted that even if significant proportions of asbestos particles have been found in drinkable water, there appears to be no incidence of cancers or other diseases related to ingested asbestos particles.
It is consequently understood that gathering asbestos can be hazardous, and even lethal over a long period of time, for the workers who are exposed to the airborne asbestos fibers. Also, if an object made from a material containing asbestos is damaged during its use, it may free asbestos particles into the air, which may lead to inhalation thereof by the persons located close to this object. For example, workers destroying a house or building structure including asbestos in its walls and/or roofing, can be exposed to significant airborne asbestos particles concentrations and may contract an asbestos-related disease.